1. Field of the Invention
This invention is in the area of touch fastening devices, specifically a fastener strip with magnetically attractable bodies that are incorporated into discrete, individually distinct areas of the strip—rather than being distributed generally throughout the volume of the strip. A process for manufacturing such a strip is also described.
2. Description of the Related Art
It can be appreciated that a seat for a vehicle or the like is configured by attaching a superficial skin member on a surface of a cushion body. In order that a person sitting on the seat can maintain a seated posture and not tire even if he or she is sitting for a long time, a structure having a concave form is employed. In a seat having such a concave form in order to prevent the superficial skin member from floating from the cushion body at the concave portion, as shown in FIG. 34, a foam molded article with a fastener strip attached to the concave portion is used as the cushion body. The fastener strip which is attached integrally to the cushion body and a mating fastener strip attached on a rear surface of the superficial skin member are adhesively engaged, so as to prevent the floating of the superficial skin member.
FIG. 9 shows a production example of a cushion body, in which a fastener strip is attached to the surface of a foam molded article in an integrated manner. The cushion body is manufactured by mounting the fastener strip in a mold with the fastening element side face-down, injecting a foam resin material into the mold, and foaming the foam resin material to form the cushion body.
As a method of fixing the fastener strip on the surface of the mold, a magnetically attractable body is generally provided on the fastener strip so as to fix the fastener strip to a magnet disposed in the mold. The magnetically attractable components have taken various forms, including metal staples, steel strips or shims, wire, porous metal webs or woven screens, and magnetically attractable particles.
U.S. Pat. No. 5,500,268, for example, discloses magnetically attractable particles which are incorporated into a foam seal also used to prevent fouling of the fastening elements during molding. U.S. Pat. Nos. 4,563,380; 4,710,414 and 4,784,890 describe the use of magnetically attractable particles which are mixed into the adhesive used to attach together various elements of the fastener strip, such as an anchor layer or a backing layer. U.S. Pat. No. 5,540,970 discloses a fastener strip having magnetically attractable particles embedded in an encasement which surrounds the hooks and thus prevents fouling; this encasement is then removed after the completion of the molding process.
Additionally, U.S. Pat. No. 5,945,193 describes a porous metal web or woven screen which is embedded into the back of the fastener base, or into a backing or substrate layer attached to the base.
As additional known examples, a magnetically attractable body can disposed on the side of the fastener strip; a soft magnetically attractable tape can be provided on a film to prevent foam resin from invading the fastening element surface upon foam-molding (Japanese Patent Application Laid-Open No. 4-109904); a thin steel strip can be clipped between the fastener strip and a lining (U.S. Pat. No. 4,673,542); many magnetically attractable members can be disposed adjacent to the edges of the opposite sides of the base of the fastener strip (U.S. Pat. No. 5,654,070); the base of the fastener strip can include a magnetic deactivate substance which acts on a magnetic attractant (U.S. Pat. No. 5,725,928); or a porous magnetically attractable web can be embedded in the base of the fastener strip (U.S. Pat. No. 5,945,193).
A magnetically attractable body can also be provided substantially all over a surface of a fastener strip in order to improve the absorption power of a magnet in the mold (Japanese Patent Application Laid-Open No. 4-109904; U.S. Pat. No. 4,673,542; U.S. Pat. No. 5,725,928; and U.S. Pat. No. 5,945,193), or many magnetically attractable members can be disposed adjacent to the edges of the opposite sides of a base of a fastener strip (U.S. Pat. No. 5,654,070).
Further, U.S. Pat. Nos. 5,725,928 and 5,932,311 describe respectively a touch fastener, and a process of making the same, wherein the magnetically attractable particles are incorporated into the entire hook and base layer, or into an entire substrate layer that is coextruded with the hook and base layer. This is accomplished by premixing ferromagnetic material into the resin stream feeding the entire extruder. U.S. Pat. No. 5,766,723 similarly discusses a fastener assembly wherein magnetically attractable particles are incorporated into the entire hook and base layer, or into an entire backing layer which is later attached to the hook and base layer.
The prior art of the previous paragraph has a major disadvantage, however, in that the magnetically attractable particles are mixed into the resin that forms the entire hook and base layer of the fastener strip, and/or the entire substrate layer if a substrate layer is used. Consequently, the magnetically attractable particles are present throughout the entire volume of the base and/or substrate, rather than being present in only those areas where magnetic attraction is desired. This process is wasteful, because it uses more magnetically attractable particles than might otherwise be needed. To the extent that magnetically attractable particles in the resin can affect other properties of the fastener strip, it can also degrade performance.
Conventional fastener strips have mainly emphasized strengthening of the magnetic force, and this approach has significant disadvantages. When such a fastener strip is initially placed on a mold, the fastener strip is immediately attracted and fixed on that position. The strip is difficult to reposition if such repositioning is needed. As a result, these fastener strips need to be repositioned by hand, one by one. It thus takes an unacceptably long time to position the fastener strips in the mold.
Thus it can be seen that a fastener strip having magnetically attractable particles incorporated into the fastener strip only in discrete, targeted areas, and a manufacturing process for such a strip, would have significant advantages over the prior art. Accordingly, several objects and advantages of the invention are:
The location of the magnetically attractable bodies can be precisely targeted within the base, within any members unitarily molded with the base, or within a substrate layer—the bodies need not be distributed across the extent of the fastener strip. As just one example, magnetically attractable particles can be incorporated only into those portions of the base that underlie foam or other types of side seals, such that the magnetic force acts only on the sides of the strip.
As another advantage, magnetically attractable particles or long magnetically attractable bodies can be incorporated only along the longitudinal center of the strip, which makes it easier to align the strip in the mold. Generally, when a fastener strip having a narrow and long magnetically attractable body is mounted in a magnetic field generated from a magnet, the magnetically-charged ends of the fastener strip naturally align with the oppositely-charged poles of the mold magnet. It is thus easier to quickly and correctly position the fastener strip in a metal mold.
The process of the invention makes it faster and easier to purge resin containing magnetically attractable particles from the extruder and other equipment. It is thus easier to cycle between extruding strips with magnetically attractable particles and those without, using the same equipment, because the entire extruder does not have to be cleaned of magnetically attractable particles. Instead, only that portion or portions through which magnetically attractable particles have traveled must be cleaned. The line or channel which introduces the magnetically attractable particles can even be turned off or on if desired. It is thereby possible to increase flexibility and reduce cycle times in the manufacturing process.
Incorporating magnetically attractable particles or magnetically attractable bodies only where needed lowers the cost of the fastener strip, by reducing waste and cutting equipment cleanup time.
To the extent that magnetically attractable particles in the resin can adversely affect other properties of the fastener strip, the invention allows one to limit those effects to specifically defined areas.
Further objects and advantages of the invention will become apparent from a consideration of the drawings and ensuing description.